伊芙

Eve was created by Stellar Blade lead Kim Hyung Tae in 2019 as the game's protagonist. Originally called "Eve 107", when designing her he wanted a character that reflected the style he had developed while working on his previous titles. While he wanted to ensure she didn't stand out too much from the game's world, her contrast with it at the same time was intended to create a sense of unease within the player. A variety of costumes for the character were additionally added for her to wear in-game to help bring out her "charm", while her animations were based on ballet and gymnastics to give her a different feel from male protagonists seen in other games. While her face was created by the development team, Eve's body is based on Korean model Shin Jae-eun using 3D scans. When asked why they chose her specifically, Kim responded that while beauty was subjective, they wanted to create what they felt was "the most attractive looking body for the user". A later update for the game added additional outfits which utilized 3D scans of a second Korean model, Yoon Seolhwa.

When developing her 3D model, the team focused attention to the back of her character model in particular, feeling it was "pretty important" due to it facing the character during most gameplay. Kim stated the emphasis on the character's beauty was a stylistic choice and not solely one for titillation, feeling that designing a purposefully glamorous character in the gaming environment at the time was "somewhat of a brave thing to be going for or attempting". He elaborated that in comparison to films, he felt video games were often scrutinized harsher by culture, with particularly harsh criticism towards "unrealistically beautiful characters". He added that when playing a game, he wanted to see a character "who is better-looking than myself", preferring something ideal over something "normal", adding that his work was "entertainment targeted for adults." To this end, he felt an ideal character was one that "can show their own charms and attractiveness without damaging the narrative or the setting of the game".

Her personality was designed to be harsher at the beginning of the game, "soldier-like" and showing little emotion or expression, but soften as the title progressed. He further expressed that when it came to the subject of her sexual appeal and using her sexuality as a weapon, Eve was unaware of "those charms that she possesses, so she's not that kind of character", though stated that may change with later installments. The developers stated that Eve's large costume selection was due to her fascination with outfits left behind on the surface of Earth, though chose not to state or demonstrate this part of her character in game.

Several pre-existing female video game characters influence her design, including Nier: Automata's 2B and P.N.03's Vanessa Z. Schneider, the latter of which inspired Eve's "action style" as well as her physical features. Prior to Stellar Blade's release, the character saw criticism in regards to how sexualized her appearance is. Kim argued that she was meant to be a character whose expression of beauty was developed with "little restrictions and no constraints", and a contrast to more "realistic" games in his view, feeling that it was fine for both character-design archetypes to coexist. He wanted to define Eve as a Korean woman, developed by Koreans and reflecting their own views on beauty, and to represent how their culture differed from other Asian cultures.